In Syria, Dave, Bushra and Chloe confront the aftermath of a brutal regime. In Somalia, Jess, Nathan and Mathilda face a deadly mix of conflict, climate change, and famine. Fierce debate follows.

The group grapple with the enormity of what they're doing. Rows erupt as they trek miles in the heat, dodge drone strikes in Syria, and shadow Lebanese police squads rounding up migrants to deport.

The long, perilous journey continues as some of the Brits experience the terror of a sea crossing and an Alpine trek. And emotions run high as the travellers meet refugees who are heading into Europe.